Binocular interaction on single units in cat striate cortex: Simultaneous stimulation by single moving slit with receptive fields in correspondence

Summary Averaged responses of binocularly-activated single units of the striate cortex of paralysed cats were studied using a single, moving visual stimulus and prisms of variable power to control the visual direction of each eye. Binocular facilitation, summation or occlusion of the monocular response occurred, depending on the type of unit and on the prism setting. Binocular stimulating conditions were optimal for a given unit when the prism setting superimposed, or very nearly superimposed, the receptive field pair on the same plane as the moving stimulus. Under these optimal conditions, most units showed summation or facilitation of the monocular responses, with a minority showing occlusion. When the prism setting was changed from the optimal value, binocular occlusion could be demonstrated in all units.Curves plotting binocular response against prism setting provided information on the specificity, temporal properties and symmetry of the binocular response. The binocular response of simple units showed great specificity with a sharply defined peak on the response curve at a particular prism setting. There was variation from one simple unit to another in the exact prism setting required to give the optimal response. A proportion of complex units, despite large receptive field size, showed binocular specificity with a very narrow range of facilitation, of the same order as that shown by simple units. Other complex units showed binocular facilitation over a wide range of prism settings.Selby Fellow of the Australian Academy of Sciences.